Carbon nanotubes have been most actively studied for the recent decade due to their various potential applications. Carbon nanotubes have excellent electric/electronic properties, low thermal expansion, high thermal conductivity, very high mechanical strength, etc. and thus have their applicability to various fields. As an example, carbon nanotubes show their applicability to electric/electronic devices, such as devices that can substitute for silicon semiconductors, field-emission display devices, electrodes, super-capacitors, etc., high-performance/high-strength polymers or ceramic nanocomposites, and applications such as hydrogen storage media, gas sensors, nanocarriers, etc. due to excellent gas absorption.
Reviewing existing methods for preparing carbon nanotubes, a solution for the synthesis of carbon nanotube fibers generally comprises a carbon source such as acetone, a catalyst precursor such as ferrocene, and an activator such as thiophene and is sprayed into a vertical electric furnace to synthesize carbon nanotube fibers. At this time, the catalyst precursor is decomposed in the vertical electric furnace to produce catalyst particles, and these particles tend to agglomerate. The agglomeration of the catalyst particles affects the physical properties such as the diameter of carbon nanotubes, and the catalyst particles that are larger than a predetermined level lose their catalytic function, which do not participate in the synthesis of carbon nanotube fibers but are present as impurities, thus adversely affecting the strength and electrical properties of carbon nanotube fibers. Therefore, there is a need to develop an effective method for preparing carbon nanotube fibers.